This invention relates to a push-pull type suspension wherein the axle is integrated to the suspension members to provide roll stability.
Trailer suspension systems must overcome numerous forces. During travel, the suspension system must provide adequate stability to the vehicle wheels to resist vibration and bouncing. In addition, roll stability must also be provided to maintain the proper position of the wheels as the trailer rounds a turn.
Often, trailer wheels are mounted on a slider. A slider is a carriage which mounts two sets of wheels and associated suspensions, brakes, air springs, etc. The slider may be moved along the length of the trailer, and fixed at any of several desired locations.
One problem that has occurred with such suspension systems is "dock walk." A trailer fixed at a loading dock has sometimes reacted to forces such as a bump at the back of the trailer by "walking" or moving a distance in response to the bump.
To resist dock walk, so-called "push-pull" suspensions have been developed. In this type suspension, the slider has a central bracket which extends downwardly between two wheels. Suspensions from the two wheels both extend to the central bracket. Thus, should a force be applied to the bracket from a first wheel, the other wheel experiences an equal and opposite force. The forces on the bracket cancel, and thus there is no force transmitted to the vehicle frame. This type of suspension system resists dock walk quite successfully. One well known type of such suspension includes a parallelogram-type suspension. Known parallelogram suspensions have proven successful in resisting dock walk, and in providing good suspension and resistance to vertically upward or downward forces on the wheels.
One problem with this general class of known suspensions, is that they have poor roll stability. When the trailer is turning a corner, the forces on the outer wheel are greater than those on the inner wheel. The suspension must resist the tendency to roll away from the greater force. In some suspensions, the roll stability has been less than desired.
One recently developed suspension utilizes a crossing stabilizer bar which extends between spaced parallelogram suspensions on opposed sides of the vehicle. This stabilizer bar adequately provides roll stability, but does increase the weight of the system. In some applications, it may be desirable to provide a lighter roll stabilizer structure.